Hi all,
Fairly new to the electronics game and I've been messing around with the HC-SR04 module. The arduino is hooked up via USB but is being powered by a 9v 0.6A plug (all I had around sadly). Anyway, there's nothing else hooked up other than the sensor and I've got the following connected:
MODULE | ARDUINO
VCC | 5V
GND | GND
TRIG | 11
ECHO | 12
I've tried plenty of sketches, consistently receiving an upper distance cutoff of "1 inch 4 cm", even when pointed at a wall, a meter or so away. If I however move my finger close the values decrease, so the lower readings seem OK albeit flaky.